Separate entrypoints in a multi-stage build are marked erroneously as an error

[mplewis]

Issue details

I want Dockerlint to properly lint my multi-stage Dockerfiles. However, it doesn't seem to support using a CMD directive in more than one stage.

Steps to reproduce/test case

Put this into Dockerfile:

FROM busybox AS base

WORKDIR /tmp
CMD ["/bin/sh"]

########################################

FROM base AS whoami

CMD ["whoami"]

Then run dockerlint Dockerfile.

Expected behavior: Dockerlint succeeds on this file.

Actual behavior:

ERROR: Multiple CMD instructions found, only line 10 will take effect

ERROR: Dockerfile failed.

Affected version(s)

0.3.9